Multi-phase switching converters are widely used in power solutions of CPU because of its good performance. For multi-phase switching converters, thermal balance is needed to make sure none of the phases is running too hot.
Usually, thermal balance is achieved by balancing the output current of each phase. Ideally, the power loss and temperature rise should be same if the phase current is the same as each other. However, considering the cooling airflow in the real system, it's very likely that the temperature is not balanced even each phase takes the same current. FIG. 1 illustrates the thermal condition of a prior multi-phase switching converter used in a CPU system. As shown in FIG. 1, the phase current is the same as each other, but there is a progressive temperature decrease because of the cooling airflow.